Some types of electrical generation equipment, such as renewable energy sources including photovoltaic solar generation sites, generate electrical energy in the form of Direct Current (DC) electrical power. The DC electrical power produced by these systems is converted by an electrical power inverter into Alternating Current (AC) electrical power that is able to be directly provided to an electrical transmission or distribution grid.
AC electrical power generally consists of what is referred to as “real” power and “reactive” power. Reactive power refers to components of AC electrical power where the electrical current is ninety degrees (90°) out of phase with the electrical voltage present on the line. Real power refers to the electrical power components where the electrical current is in-phase with the voltage. In general, AC electrical power often has current that is not completely in-phase with voltage and thus some reactive power is present along with real power. The presence of reactive power on an electrical transmission or distribution line causes the voltage that is present on the line to vary from a nominal voltage for that line. In some examples, devices are installed along electrical transmission or distribution lines that are able to produce or consume reactive power. These devices operate to regulate the voltage on the transmission line to maintain a stable and constant voltage by varying the amount of reactive power they produce or consume based on measured deviations of voltage on the transmission or distribution line where that device is located. Such regulation reduces that voltage deviation and reduces the difference between the present and the nominal voltage on the electrical transmission or distribution system.
Some electrical power inverters used to convert DC electrical power from renewable energy sources to AC electrical power are able to be configured or adjusted as they are operating to produce or consume a specified amount of reactive electrical power. Some electrical power inverters are able to produce or consume an amount of reactive power equal to the inverter's full power rating, even when the amount of DC electrical power being provided to the electrical power inverter is low. The real power produced on the AC output of the electrical power inverter is limited by the amount of DC power that is provided as in input to the electric power inverter. In such examples when the DC power input to the electric power inverter is low, the electric power inverter is able to produce or consume a relatively large amount of reactive power even while it produces only a small amount of real power.